1. Field of the Invention
The invention relates generally to methods and apparati for determining concentration(s) of one or more analytes in a sample using plasmonic excitations and apparati and methods for designing systems for such concentration determination.
2. Technical Background
Surface Plasmon Polaritons (SPP) are electromagnetic excitations at the surface of metals and in metal nanoparticles.
A number of recent reports [1-6] show that surface plasmon excitations in metal particles or metal films can cause an enhancement of the light absorption efficiency of organic [2,4] and inorganic photodetectors [1, 3, 5-6].
In biosensing, the importance of plasmonics relies in high optical energy confinement and strong local enhancement of electric fields. Biorecognition is achieved in (localized) surface plasmon resonance ((L)SPR) biosensors [Hats, A. J.; Van Duyne, R. P. Anal. Bioanal. Chem. 2004, 379, 920; Frederix, F. et al. s, G. Anal. Chem. 2003, 75, 6894] through the detection of (L)SPR spectral changes caused by adsorbate-induced changes in local dielectric constant. In a very common configuration, the SPR spectrum of a nanoparticle surface or nanostructured surface is studied with an optical detector in the far field at large distance from the metal particle or film [7].